AROS Wiki Book User guide for AROS, which contains a significant section on developing for AROS. The “porting” section has relevant information for updating old Amiga software to more recent AmigaOS3 or 4 setups as well (information on differences between SAS/C and gcc, most of which applies to vbcc too, in particular)

Documentation of the AMOS file formats - AMOS is a BASIC style language for the Amiga with extensive graphics and sound support; this documentation is most interesting for people who wish to manipulate source code written in AMOS in external tools.